VEKMES 



165 



canal is examined a fold called the typhlosole running 

 its entire length will be noticed. This fold practically 

 doubles the absorptive surface of the canal so that in the 

 passage of food from the mouth to anus there is time 



Fi«. 94.— A, diagram of a longitudinal section of the earthworm. B, diagram of a 

 cross section. C, diagram showing the principal organs, al, alimentary canal ; 

 an, anus; ds, dissepiments; d.v. y dorsal blood vessel; s.i., ventral blood 

 vessel ; c.v., circular blood vessel ; n, nephridia or excretory organs ; e.g., 

 cerebral ganglia ; v.g., ventral chain of ganglia ; o.d., oviduct ; o, ovary ; m, 

 mouth ; c.ce., body cavity. (From Sedgwick and Wilson.) 



and place for the digestion and absorption of sufficient 

 nourishment (Fig. 97). In the starfish where the dis- 

 tance between mouth and anus is very short the same 

 thing is accomplished by the large pouched-stomachs 

 whose folds increase enormously the digestive surface; 

 and in higher animals it is accomplished by the in- 

 creased length of the canal, which in man reaches five 

 or six times the length of the body. 



Circulatory System. — The circulatory system is well 

 defined. The vivid red blood makes the large vessels 

 which run longitudinally on the dorsal and ventral sides 

 noticeable through the skin. They are connected by a 



